WO2012014838A1 - Medical actuator - Google Patents

Abstract

Provided is a medical actuator which is capable of remotely controlling a tool attached to the tip of an elongated pipe section to change the attitude thereof with high accuracy and preventing the friction between mutually contacting portions without having detrimental effects on a living body. The medical actuator includes an elongated spindle guide section (3), a tip member (2) provided at the tip thereof so as to be freely changeable in attitude, and a tool (1) rotatably attached to the tip member (2). The tip member (2) rotatably supports a spindle (13) that retains the tool (1). The spindle guide section (3) includes a rotating shaft (22) for transferring rotation to the spindle (13), and a guide hole (30a) which penetrates from end to end. The medical actuator allows an attitude control member (31) to be axially moved back and forth and thereby change the attitude of the tip member (2), the attitude control member (31) being retractably inserted in the guide hole (30a). A DLC film is formed on the surface of at least one mutually contacting portion of a plurality of parts, the parts moving relative to each other.

Description

Medical actuator Related applications

This application claims the priority of Japanese Patent Application No. 2010-171593 filed on July 30, 2010, and is incorporated herein by reference in its entirety.

This invention relates to a medical actuator capable of changing the posture of a tool by remote control.

For example, there are medical actuators used for bone processing. The medical actuator remotely controls a tool provided at the end of a long and narrow pipe portion having a linear shape or a curved shape. However, since the conventional medical actuator only controls the rotation of the tool by remote control, it is difficult to process a complicated shape or a part that is difficult to see from the outside. Further, in drilling, it is required that not only a straight line but also a curved shape can be processed. Furthermore, in the cutting process, it is required that a deep part inside the groove can be processed.

In the field of orthopedics, there is an artificial joint replacement surgery in which a joint that has been worn out due to bone aging or the like is replaced with a new artificial one. In this operation, it is necessary to process the patient's living bone so that the artificial joint can be inserted. In order to increase the adhesive strength between the living bone and the artificial joint after the operation, the shape of the artificial joint is required. It is required to process with high accuracy.

For example, in hip joint replacement surgery, an artificial joint insertion hole is formed in the medullary cavity at the center of the femur bone. In order to maintain the contact strength between the artificial joint and the bone, it is necessary to increase the contact area between them, and the hole for inserting the artificial joint is processed into an elongated shape extending to the back of the bone. As a medical actuator used for such a bone cutting process, a tool is rotatably provided at the distal end of an elongated pipe portion, and by driving a rotational drive source such as a motor provided on the proximal end side of the pipe portion, There exists a thing of the structure which rotates a tool via the rotating shaft arrange | positioned inside (for example, patent document 1). In this type of medical actuator, the rotating part exposed to the outside is only the tool at the tip, so that the tool can be inserted deep into the bone.

In artificial joint replacement surgery, skin incision and muscle cutting are involved. That is, the human body must be damaged. In order to minimize the scratches, the pipe part may not be straight but may be appropriately curved. In order to cope with such a situation, there are the following conventional techniques. For example, in Patent Document 2, an intermediate portion of a pipe portion is bent twice, and the axial center position on the distal end side and the axial center position on the proximal end side of the pipe portion are shifted. There are other known cases where the axial position of the pipe portion is shifted between the tip end side and the axial center side. In Patent Document 3, the pipe portion is rotated 180 degrees.

JP 2007-301149 A U.S. Pat. No. 4,466,429 US Pat. No. 4,265,231 JP 2001-17446 A

If there is a wide gap between the living bone and the artificial joint with the artificial joint inserted in the artificial bone insertion hole of the living bone, the adhesion time after the operation becomes longer, so the gap is as narrow as possible. desirable. It is also important that the contact surface between the living bone and the artificial joint is smooth, and high accuracy is required for processing the hole for inserting the artificial joint. However, no matter what the shape of the pipe part, the operating range of the tool is limited by the shape of the pipe part. It is difficult to process the artificial joint insertion hole so that the gap is narrow and the contact surface of both is smooth.

Generally, the bones of patients undergoing artificial joint replacement are often weakened due to aging or the like, and the bones themselves may be deformed. Therefore, it is more difficult to process the artificial joint insertion hole than is normally conceivable.

Therefore, the present applicant tried to make it possible to remotely change the posture of the tool provided at the tip for the purpose of relatively easily and accurately processing the hole for inserting the artificial joint. . This is because, if the posture of the tool can be changed, the tool can be held in an appropriate posture regardless of the shape of the pipe portion. However, since the tool is provided at the tip of the elongated pipe portion, there are many restrictions in providing a mechanism for changing the posture of the tool, and a device for overcoming it is necessary. Further, it is expected that the pipe portion has a curved portion, and it is desired that the posture changing operation can be surely performed even in that case.

Note that some medical actuators that do not have an elongated pipe part can change the position of the part where the tool is provided relative to the hand-held part (for example, Patent Document 4), but the position of the tool can be changed remotely. Nothing has been proposed to make it happen.

In the case of a configuration in which the posture of the tool is changed by remote operation, there are many mutual contact locations where a plurality of parts move relative to each other, and friction occurs at these mutual contact locations. This friction may cause wear of parts, or hysteresis may occur in the relationship between the command value of the drive unit and the actual operation, and the positioning accuracy of the tool may be reduced. Further, if the wear is severe, there is a risk that the wear powder adversely affects the living body. For this reason, it is necessary to suppress friction at the mutual contact location, but it is not preferable for a living body to use a lubricant such as grease. Therefore, it is a problem to suppress friction at the mutual contact points without adversely affecting the living body.

According to the present invention, the posture of a tool provided at the tip of an elongated pipe portion can be accurately changed by remote control, and the friction at the mutual contact point where a plurality of parts move relative to each other without adversely affecting the living body is suppressed. It is to provide a medical actuator that can be used.

The medical actuator according to the present invention includes an elongated spindle guide portion, a tip member that is attached to the tip of the spindle guide portion via a tip member connecting portion so that the posture can be freely changed and rotatably supports a tool, A tool rotation drive source for rotating a tool; and a posture change drive source for operating the posture of the tip member. The tip member rotatably supports a spindle holding the tool, and the spindle guide portion Has a rotation shaft for transmitting the rotation of the tool rotation drive source to the spindle and guide holes penetrating both ends, and the tip member moves forward and backward by contacting the tip member. A flexible posture operation member for changing the posture is inserted into the guide hole so as to freely advance and retract, and the posture control member is advanced and retracted by the posture change drive source. A Chueta, at least one, is obtained by forming a DLC film on the surface of a plurality of component mutual contact points of the relative movement to each other. The DLC film refers to a film or layer made of DLC alone or a film or layer mainly composed of DLC.

According to this configuration, the bone or the like is cut by the rotation of the tool provided on the tip member. In this case, when the posture operation member is moved forward and backward by the posture change drive source, the tip of the posture operation member acts on the tip member, so that the posture can be changed to the tip of the spindle guide portion via the tip member connecting portion. The position of the tip member attached to is changed. The posture changing drive source is provided at a position away from the tip member, and the posture change of the tip member is performed by remote control. Since the posture operation member is inserted into the guide hole, the posture operation member does not shift in the direction intersecting the longitudinal direction, and can always act properly on the tip member, and the posture change operation of the tip member Is done accurately. In addition, since the posture operation member is flexible, the posture changing operation is reliably performed even when the spindle guide portion is curved.

When a DLC film is formed on the surface of the mutual contact location, the friction coefficient at the mutual contact location can be lowered without using a lubricant such as grease. For example, the coefficient of friction can be about 0.1. For this reason, a smooth operation can be realized without generating an operation like stick-slip due to friction. Further, when a DLC film is formed on the surface of the mutual contact location, the wear resistance at the mutual contact location is improved, and the operation accuracy can be maintained at a high level. Furthermore, generation of wear powder can be prevented. Since the DLC film is biocompatible, it is suitable for the surface treatment of a medical actuator used in surgery or the like.

In this invention, one of the mutual contact points is the tip member connecting portion, and the tip member connecting portion is configured such that the guide portion on the spindle guide portion side and the guided portion on the tip member side are the center of the spindle. In the case of a structure in which spherical or cylindrical guide surfaces each having a center of curvature located on a line are in contact with each other, a DLC film is provided on the guide surface which is the outer peripheral surface of the guide surface of the guide portion and the guide surface of the guided portion. It is good to form.

The tip member connecting portion is a portion that operates when the tip member is changed in posture with respect to the spindle guide portion. Therefore, by forming the DLC film on the tip member connecting portion, the friction of the tip member connecting portion can be reduced and a smooth posture changing operation of the tip member can be realized. Of the guide surface of the guide portion and the guide surface of the guided portion, the guide surface that is the outer peripheral surface is exposed to the outside in the state before assembly, and therefore forms a DLC film rather than the guide surface that is the inner peripheral surface. It is easy to perform processing.

In the present invention, one of the mutual contact points is a rotation transmission portion that connects the spindle and the rotation shaft so as to be able to transmit rotation, and the rotation transmission portion is provided on one of the spindle and the rotation shaft. In the case of a structure in which the protrusion and the groove provided on the other are engaged with each other to transmit the rotation, it is preferable to form a DLC film on the surface of the protrusion.

Further, one of the mutual contact portions is a rotation transmission portion that connects the spindle and the rotation shaft so as to be able to transmit rotation, and the rotation transmission portion connects protrusions provided on the spindle and the rotation shaft to each other. When the structure is configured to transmit rotation by engaging, it is preferable to form a DLC film on the surface of both or one of the protrusion of the spindle and the protrusion of the rotation shaft.

The rotation transmission part is a part that transmits high-speed rotation from the rotating shaft to the spindle regardless of the attitude of the tip member, and particularly wear resistance is required. By forming the DLC film on the rotation transmitting portion, it is possible to improve friction resistance and to transmit stable rotation. In both the structure in which the rotation transmitting portion engages the protrusion and the groove to transmit the rotation, and the structure in which the protrusion engages with each other to transmit the rotation, the surface of the protrusion is external before the assembly. Therefore, it is easy to perform the process of forming the DLC film.

In this invention, when one of the mutual contact locations is a contact portion between the inner peripheral surface of the guide hole and the outer peripheral surface of the posture operation member, it is preferable to form a DLC film on the outer peripheral surface of the posture operation member. .

¡The attitude control member advances and retreats while being guided by the inner peripheral surface of the guide hole. At that time, friction occurs due to contact with the inner peripheral surface of the guide hole. When the DLC film is formed on the outer peripheral surface of the posture operation member, the friction coefficient between the inner peripheral surface of the guide hole and the outer peripheral surface of the posture operation member is reduced, and the posture operation member is smoothly advanced and retracted. Since the outer peripheral surface of the posture operation member is exposed to the outside in the state before assembly, it is easy to perform the process of forming the DLC film.

In this invention, when an angle formed by a perpendicular perpendicular to a tangent at a contact point between the tip member and the posture operation member and a center line of the rotating shaft is α, α> 0 ° and the mutual contact When one of the locations is a contact portion between the tip member and the posture operation member, a DLC film may be formed on both or one surface of the contact portion on the tip member side and the contact portion on the posture operation member side.

In the posture change operation of the tip member, the tip of the posture operation member pushes the contact surface of the tip member with the posture operation member, so that the tip member swings and changes its posture. At that time, the angle formed between the contact surface of the tip member with the posture operation member is perpendicular to the advancing / retreating direction of the posture operation member, that is, the perpendicular perpendicular to the tangent at the contact point between the tip member and the posture operation member When α is α, when α = 0 °, no slip occurs between the tip member and the posture operation member, and the tip member cannot swing. However, if α> 0 °, it is possible to swing the tip member while sliding the tip member relative to the posture operation member, and the tip member can be smoothly changed in posture.

As described above, when the posture operation member applies an acting force to the tip member while the contact portion on the tip member side and the contact portion on the posture operation member side are in sliding contact with each other, the tip member and the posture operation member Friction occurs at the contact area. Due to the resistance caused by this friction, an angle range in which the tip member cannot slide with respect to the posture operation member, that is, a friction angle exists among the angles α. This friction angle is proportional to the friction coefficient of the contact portion between the tip member and the posture operation member. Therefore, by forming a DLC film on the surface of both or one of the contact part on the tip member side and the contact part on the posture operation member, and reducing the friction coefficient of the contact part between the tip member and the posture operation member, The angle is reduced, and the posture of the tip member can be changed smoothly. Also, if the friction angle is reduced, the amount of change in the posture of the tip member relative to the amount of advancement / retraction of the posture operation member is reduced, so that the posture of the tip member can be controlled with fine resolution.

In the present invention, one of the mutual contact portions may be a rotation support member that rotatably supports the rotation shaft in the spindle guide portion. When the rotation support member is a rolling bearing, it is preferable to form a DLC film on both or one of the surface of the ball of the rolling bearing and the rolling surface of the inner and outer rings.

Also for the rotation support member, it is not preferable to use a lubricant such as grease, and it is preferable to improve the wear resistance by forming a biocompatible DLC film on the surface. When the rotation support member is a rolling bearing, since the surface of the ball and the rolling surface of the inner and outer rings are exposed to the outside in the state before assembly, the DLC film can be easily formed.

In the medical actuator according to the present invention, each component may be made of a biocompatible material. The biocompatible material is, for example, titanium or stainless steel material. If such a component made of a biocompatible material is used, even if it is used for surgery or the like, it does not adversely affect the living body.

In the present invention, the spindle guide portion may have a curved portion. Since the posture operation member is flexible, even if the spindle guide portion has a curved portion, it can be advanced and retracted in the guide hole.

In the present invention, the DLC film is preferably formed by physical vapor deposition. This is because the DLC film formed by physical vapor deposition is excellent in wear resistance. Of these, the unbalanced magnetron sputtering method is preferable.

In this invention, it is preferable to form an intermediate layer containing chromium and tungsten between the substrate and the DLC film. When the intermediate layer is formed, the adhesion between the substrate and the DLC film can be improved.

In the present invention, the thickness of the DLC film is preferably 0.3 to 3 μm.

Any combination of at least two configurations disclosed in the claims and / or the specification and / or drawings is included in the present invention. In particular, any combination of two or more of each claim in the claims is included in the present invention.

The present invention will be more clearly understood from the following description of preferred embodiments with reference to the accompanying drawings. However, the embodiments and drawings are for illustration and description only and should not be used to define the scope of the present invention. The scope of the invention is defined by the appended claims. In the accompanying drawings, the same reference numerals in a plurality of drawings indicate the same or corresponding parts.
It is a figure which shows schematic structure of the medical actuator concerning 1st Embodiment of this invention. It is a figure which shows schematic structure of the medical actuator concerning 2nd Embodiment of this invention. (A) is a longitudinal sectional view of the tip member and spindle guide portion of the medical actuator shown in FIG. 1, and (B) is a sectional view taken along line IIIB-IIIB. (A) is a top view of an example of the rotation transmission part of the medical actuator, (B) is the front view, (C) is the side view which abbreviate | omitted one part. (A) is a plan view of another example of the rotation transmission unit, (B) is a front view thereof, and (C) is a side view with a part omitted. (A) is a longitudinal sectional view showing a combination of a control system and a sectional view of the tool rotation drive mechanism and posture changing drive mechanism of the medical actuator, and (B) is a sectional view taken along the line VIB-VIB. It is a figure which shows the DLC film formation location of a front-end | tip member connection part. (A) is a plan view showing a DLC film forming portion of the rotation transmitting portion shown in FIGS. 4 (A) to (C), and (B) is a side view thereof. FIG. 5A is a plan view showing a DLC film forming portion of the rotation transmitting portion shown in FIGS. 5A to 5C, and FIG. 5B is a side view thereof. It is a figure which shows the DLC film formation location of an attitude | position operation member. It is a figure which shows an example of the DLC film formation location of a rolling bearing. It is a figure which shows the example from which the DLC film formation location of a rolling bearing differs. (A) is a longitudinal sectional view of different tool rotation drive mechanism and posture change drive mechanism, and (B) is a sectional view taken along line XIIIB-XIIIB. (A) is a longitudinal cross-sectional view of yet another tool rotation drive mechanism and posture change drive mechanism, and (B) is a cross-sectional view taken along the line XIVB-XIVB. It is a figure which shows schematic structure of the medical actuator concerning 3rd Embodiment of this invention. (A) is a longitudinal sectional view of the tool rotation drive mechanism and posture change drive mechanism of the medical actuator, and (B) is a sectional view taken along line XVIB-XVIB. It is a longitudinal cross-sectional view of the flexible wire for tool rotation of the drive mechanism for tool rotation. It is a longitudinal cross-sectional view of the attitude change flexible wire of the attitude change drive mechanism. (A) is a longitudinal sectional view of a distal end member and a spindle guide portion of a medical actuator according to a fourth embodiment having different mechanisms for changing the posture of the distal end member, and (B) is a sectional view taken along the line XIXB-XIXB. (A) is a longitudinal sectional view of a distal end member and a spindle guide portion of a medical actuator according to a fifth embodiment in which the mechanism for changing the posture of the distal end member is further different, and (B) is a sectional view taken along the line XXB-XXB. (A) is a longitudinal sectional view of a distal end member and a spindle guide portion of a medical actuator according to a sixth embodiment in which the mechanism for changing the posture of the distal end member is further different, and (B) is a sectional view taken along line XXIB-XXIB. (A) is a longitudinal sectional view of the tool rotation drive mechanism and posture change drive mechanism of the medical actuator shown in FIGS. 20 (A) and 20 (B) or FIGS. 21 (A) and 21 (B), and FIG. It is a sectional view taken along line XXIIB-XXIIB. 20A is a longitudinal cross-sectional view of a tool rotation drive mechanism and a posture change drive mechanism that are different from the medical actuator shown in FIGS. 20A and 20B or FIGS. 21A and 21B, and FIG. It is the XXIIIB-XXIIIB sectional view taken on the line.

1 and 2 are diagrams showing a schematic configuration of a medical actuator according to first and second embodiments of the present invention. Each medical actuator includes a distal end member 2 that holds a rotary tool 1, an elongated spindle guide portion 3 that is attached to the distal end of the distal end member 2 so that its posture can be changed, and a proximal end of the spindle guide portion 3. Are coupled to each other, and a controller 5 that controls the tool rotation drive mechanism 4b and the attitude change drive mechanism 4c in the drive part housing 4a. The drive unit housing 4a constitutes the drive unit 4 together with the built-in tool rotation drive mechanism 4b and posture changing drive mechanism 4c.

The internal structure of the tip member 2 and the spindle guide portion 3 will be described with reference to FIGS. 3 (A), 3 (B) to 5 (A) to 5 (C). 3 (A) and 3 (B) show the medical actuator of FIG. 1, but when the spindle guide 3 is straight as shown in FIG. 1, the spindle guide 3 is curved as shown in FIG. Even in the case of the shape, the internal structures of the tip member 2 and the spindle guide portion 3 are basically the same.

The tip member 2 has a spindle 13 rotatably supported inside a substantially cylindrical housing 11 by a pair of bearings 12. The spindle 13 has a cylindrical shape with an open end, and the shank 1a of the tool 1 is inserted into the hollow portion in a fitted state, and the shank 1a is non-rotatably coupled by the rotation prevention pin 14. The tip member 2 is attached to the tip of the spindle guide portion 3 via the tip member connecting portion 15. The tip member connecting portion 15 is a means for supporting the tip member 2 so that the posture thereof can be freely changed, and includes a spherical bearing. Specifically, the distal end member connecting portion 15 includes a guided portion 11 a that is a reduced inner diameter portion of the proximal end of the housing 11 and a hook-shaped portion of a retaining member 21 that is fixed to the distal end of the spindle guide portion 3. It is comprised with the guide part 21a. The guide surfaces F1 and F2 that are in contact with each other 11a and 21a are spherical surfaces having a center of curvature O located on the center line CL1 of the spindle 13 and having a smaller diameter toward the proximal end side. As a result, the tip member 2 is prevented from being detached from the spindle guide portion 3 and is supported so as to be freely changeable in posture. In this example, since the tip member 2 is configured to change the posture around the X axis passing through the center of curvature O, even if the guide surfaces F1 and F2 are cylindrical surfaces whose axis is the X axis passing through the center of curvature O. Good.

The spindle guide portion 3 has a rotating shaft 22 that transmits the rotational force of the tool rotation drive source 41 (FIG. 6A) in the drive portion housing 4a to the spindle 13. In this example, the rotating shaft 22 is a wire and can be elastically deformed to some extent. As the material of the wire, for example, metal, resin, glass fiber or the like is used. The wire may be a single wire or a stranded wire.

The spindle 13 and the rotating shaft 22 are connected to each other via a rotation transmitting portion 23 that functions as a universal joint so that the rotation can be transmitted. For example, as shown in FIGS. 4A to 4C, the rotation transmitting portion 23 engages the projections 13a and 22a provided at the proximal end of the spindle 13 and the distal end of the rotating shaft 22 with each other, The rotation is transmitted from the rotary shaft 22 to the spindle 13. In the case of this example, the protrusions 13a on the spindle 13 side are columnar shapes extending in parallel with the center line CL1 of the spindle 13, and are arranged at equal intervals in two places in the circumferential direction. The protrusion 22a on the rotating shaft 22 side has a cylindrical shape extending from the tip of the rotating shaft 22 in a direction perpendicular to the center line CL2 of the rotating shaft 22, and both ends thereof are respectively between the two protrusions 13a on the spindle 13 side. Intervene. The center of the connecting portion between the protrusion 13a on the spindle 13 side and the protrusion 22a on the rotating shaft 22 side is at the same position as the center of curvature O of the guide surfaces F1 and F2. With this configuration of the rotation transmitting portion 23, rotation can be transmitted from the rotating shaft 22 to the spindle 13 regardless of the posture of the tip member 2 with respect to the spindle guide portion 3.

Further, as shown in FIGS. 5A to 5C, the rotation transmitting portion 23 engages a protrusion 22b provided on one of the spindle 13 and the rotating shaft 22 with a groove 13b provided on the other. Thus, the rotation may be transmitted from the rotary shaft 22 to the spindle 13. In the case of this example, a groove 13b extending in a direction orthogonal to the center line CL1 of the spindle 13 is provided at the base end of the spindle 13 and extends in a direction orthogonal to the center line CL2 of the rotation shaft 22 at the tip of the rotation shaft 22. A protrusion 22b is provided. The center of the connecting portion between the groove 13b and the protrusion 22b is at the same position as the center of curvature O of the guide surfaces F1 and F2. Even with the configuration of the rotation transmitting portion 23, the rotation can be transmitted from the rotating shaft 22 to the spindle 13 regardless of the posture of the tip member 2 with respect to the spindle guide portion 3.

As shown in FIGS. 3A and 3B, the spindle guide portion 3 has an outer pipe 25 that is an outer shell of the spindle guide portion 3, and the rotating shaft 22 is located at the center of the outer pipe 25. . The rotating shaft 22 is rotatably supported by a plurality of rolling bearings 26 that are arranged apart from each other in the axial direction. The rolling bearing 26 is a rotation support member that rotatably supports the rotary shaft 22 in the spindle guide portion 3. Between each rolling bearing 26, spring elements 27A and 27B for generating a preload on the rolling bearing 26 are provided. The spring elements 27A and 27B are, for example, compression coil springs. There are an inner ring spring element 27A for generating a preload on the inner ring of the rolling bearing 26 and an outer ring spring element 27B for generating a preload on the outer ring, which are arranged alternately. The retaining member 21 is fixed to the pipe end portion 25a of the outer pipe 25 by a fixing pin 28, and rotatably supports the distal end portion of the rotary shaft 22 via a rolling bearing 29 at the distal end inner peripheral portion thereof. The pipe end portion 25a may be a separate member from the outer pipe 25 and may be joined by welding or the like.

Between the inner diameter surface of the outer pipe 25 and the rotary shaft 22, one guide pipe 30 penetrating at both ends is provided, and the posture operation member 31 advances and retreats in the guide hole 30 a which is the inner diameter hole of the guide pipe 30. It is inserted freely. In this example, the posture operation member 31 includes a wire 31a and columnar pins 31b provided at both ends thereof.

The distal end of the columnar pin 31b on the distal end member 2 side is spherical, and is in contact with the proximal end surface 11b of the housing 11 which is a contact surface with the posture operation member 31 of the distal end member 2. The base end surface 11b of the housing 11 is an inclined surface closer to the spindle guide portion 3 and the posture operation member 31 side toward the outer diameter side, and rotates with a perpendicular PL perpendicular to the tangent at the contact point P between the tip member 2 and the posture operation member 31. When the angle formed by the center line CL2 of the shaft 22 is α, α> 0 ° is always established. In the case of this embodiment, the base end surface 11b of the housing 11 has a linear cross-sectional shape. If the base end surface 11b is a plane that is not orthogonal to the center line of the posture operation member 31, the relationship of α> 0 ° is always maintained. If the cross-sectional shape is a straight line, the processing is relatively easy, and thus the manufacturing cost can be reduced. The tip of the columnar pin 31b on the drive unit housing 4a side is also spherical, and is in contact with the side surface of a lever 43b (FIGS. 6A and 6B) described later.

For example, compression is provided between the proximal end surface of the housing 11 of the distal end member 2 and the distal end surface of the outer pipe 25 of the spindle guide portion 3 at a position 180 degrees relative to the circumferential position where the posture operation member 31 is located. A restoring elastic member 32 made of a coil spring is provided. The restoring elastic member 32 acts to urge the tip member 2 toward a predetermined posture.

Further, between the inner diameter surface of the outer pipe 25 and the rotary shaft 22, as shown in FIG. 3B, a plurality of lines are provided on the same pitch circle C as the guide pipe 30 separately from the guide pipe 30. A reinforcing shaft 34 is arranged. These reinforcing shafts 34 are for ensuring the rigidity of the spindle guide portion 3. The intervals between the guide pipe 30 and the reinforcing shaft 34 are equal. The guide pipe 30 and the reinforcing shaft 34 are in contact with the inner diameter surface of the outer pipe 25 and the outer diameter surface of the rolling bearing 26. Thereby, the outer diameter surface of the rolling bearing 26 is supported.

FIG. 6A shows the tool rotation drive mechanism 4b and the posture change drive mechanism 4c in the drive unit housing 4a. The tool rotation drive mechanism 4b includes a tool rotation drive source 41 controlled by the controller 5 (FIGS. 1 and 2). The tool rotation drive source 41 is, for example, an electric motor, and its output shaft 41 a is coupled to the proximal end of the rotation shaft 22.

The posture changing drive mechanism 4 c includes a posture changing drive source 42 controlled by the controller 5. The posture changing drive source 42 is, for example, an electric linear actuator, and the movement of the output rod 42 a moving in the left-right direction in FIG. 6A is transmitted to the posture operating member 31 via the lever mechanism 43. The posture changing drive source 42 may be a rotary motor.

The lever mechanism 43 has a lever 43b that is rotatable around a support shaft 43a. The force of the output rod 42a acts on an action point P1 that is a long distance from the support shaft 43a in the lever 43b. The force is applied to the posture operation member 31 at the force point P <b> 2 having a short distance, and the output of the posture changing drive source 42 is increased and transmitted to the posture operation member 31. When the lever mechanism 43 is provided, a large force can be applied to the posture operation member 31 even with a linear actuator with a small output, and thus the linear actuator can be downsized. The rotary shaft 22 passes through an opening 44 formed in the lever 43b. Instead of providing an electric actuator or the like, the posture of the tip member 2 may be remotely operated manually.

The posture changing drive mechanism 4c is provided with a movement amount detector 45 for detecting the movement amount of the posture changing drive source 42. The detection value of the movement amount detector 45 is output to the posture detection means 46. The posture detection means 46 detects the tilt posture around the X axis (FIG. 3B) of the tip member 2 based on the output of the movement amount detector 45. The posture detection means 46 has relationship setting means (not shown) in which the relationship between the tilt posture and the output signal of the motion amount detector 45 is set by an arithmetic expression or a table, and the relationship is determined from the input output signal. The tilting posture is detected using setting means. This posture detection means 46 may be provided in the controller 5 or may be provided in an external control device.

The posture changing mechanism 4c is provided with a wattmeter 47 for detecting the amount of power supplied to the posture changing drive source 42, which is an electric actuator. The detected value of the supplied wattmeter 47 is output to the load detecting means 48. The load detection means 48 detects the load acting on the tip member 2 based on the output of the wattmeter 47. The load detection means 48 has relation setting means (not shown) in which the relation between the load and the output signal of the supplied wattmeter 47 is set by an arithmetic expression or a table, and the relation setting means is determined from the input output signal. The load is detected using. The load detecting means 48 may be provided in the controller 5 or may be provided in an external control device.

The controller 5 controls the tool rotation drive source 41 and the posture change drive source 42 based on the detected values of the posture detection means 46 and the load detection means 48. Details of the control will be described later.

This medical actuator is used, for example, to cut the medullary cavity of a bone in an artificial joint replacement operation, and is used by inserting all or a part of the distal end member 2 into a patient's body at the time of surgery. Alternatively, the middle part of the spindle guide part 3 is inserted into the patient's body for use. For this reason, biocompatible materials are used for the components constituting the tip member 2 and the spindle guide portion 3. The biocompatible material is, for example, titanium or stainless steel (SUS304, SUS316, etc.).

In this medical actuator, there are mutual contact points of a plurality of parts that move relative to each other. A DLC film is formed on the surface of each mutual contact portion for the purpose of suppressing friction. The DLC film refers to a film or layer made of DLC (diamond-like carbon) alone or a film or layer mainly composed of DLC. The DLC film is sometimes referred to as a hard carbon film. The thickness of the DLC film is preferably 0.3 to 3 μm. In addition, the film thickness said here contains the metal intermediate | middle layer demonstrated later.

DLC is a mixture of diamond and graphite, and is an intermediate structure between the two. DLC is as hard as diamond and has excellent properties such as wear resistance, solid lubricity, thermal conductivity, chemical stability, and corrosion resistance. Terms used almost synonymously with DLC include hard amorphous carbon, amorphous carbon, hard amorphous carbon, i-carbon, and diamond-like carbon. These terms are not clearly distinguished. In this specification, the terms mentioned above are also included in the DLC. These DLC are biocompatible materials.

There are a physical vapor deposition method and a chemical vapor deposition method as a method for forming a DLC film. Examples of physical vapor deposition include sputtering, unbalanced magnetron sputtering (UBMS), arc ion plating, low pressure arc discharge with filter (FCVA: Filtered Cathodic Vacuum Arc), and filtered arc. (Filtered Arc Deposition) etc. can be adopted. In the chemical vapor deposition method, for example, a plasma ion implantation / film formation method (PBII method, Plasma Source Ion Implantation), a direct current plasma CVD method (Chemical Vapor Deposition), a pulsed DC plasma CVD method, a thermal CVD method, a photo CVD method, or the like is employed. be able to. Any method may be adopted, but a physical vapor deposition method excellent in wear resistance of the formed DLC film is preferable, and an unbalanced magnetron sputtering method is particularly preferable.

In order to improve the adhesion between the substrate and the DLC film, it is preferable to form a metal intermediate layer between the substrate and the DLC film. Examples of the metal used for the metal intermediate layer include chromium (Cr), titanium (Ti), tungsten (W), silicon (Si), aluminum (Al), nickel (Ni), molybdenum (Mo), niobium (Nb), and the like. good. In order to further improve the adhesion, the surface layer may be a DLC single layer film by gradually increasing the amount of carbon contained in the metal layer toward the surface layer side. Further, a tungsten carbide layer (WC layer) or a composite layer of tungsten carbide and DLC (WC-C layer) may be formed in a multilayer state on the chromium layer (Cr layer). The hardness difference between the base material and the DLC layer may be relaxed by gradually changing the hardness of the DLC layer from the base material side to the surface side.

Furthermore, in order to improve the function, the chromium (Cr), titanium (Ti), tungsten (W), silicon (Si), aluminum (Al), nickel (Ni), molybdenum (Mo), niobium (Nb) are formed on the DLC layer. At least one kind of metal such as may be added.

Hereinafter, the DLC film formation location of each mutual contact location will be described. FIG. 7 shows a DLC film formation location when the mutual contact location is the tip member connecting portion 15 (FIG. 3A). The tip member connecting portion 15 is composed of a guide portion 21a on the spindle guide portion 3 side and a guided portion 11a on the tip member 2 side, and if a DLC film is formed on one of the guide surfaces F1 and F2, both. In this example, the DLC film 100 is formed on the guide surface F1 of the guide portion 21a. The reason is that the guide surface F1 of the guide portion 21a is the outer peripheral surface, the guide surface F2 of the guided portion 11a is the inner peripheral surface, and the guide surface F1 that is the outer peripheral surface is exposed to the outside in the state before assembly. This is because the process of forming the DLC film 100 is easy to perform. Thus, by forming the DLC film 100 on the guide surface F1, the friction of the tip member connecting portion 15 can be reduced, and a smooth posture changing operation of the tip member 2 can be realized.

8A and 8B show the DLC film formation location when the mutual contact location is the rotation transmission portion 23 of FIGS. 4A to 4C. The rotation transmitting portion 23 is obtained by engaging a protrusion 13a (FIGS. 4A to 4C) provided on the spindle 3 and a protrusion 22a provided on the rotating shaft 22 with each other. In this example, the DLC film 101 is formed on the surface of the protrusion 22 a provided on the rotating shaft 22. A DLC film may be formed on the surface of the protrusion 13a provided on the spindle 3 (not shown). Since the surface of any of the protrusions 13a and 22a is exposed to the outside before the assembly, the process of forming the DLC film 101 can be easily performed. Thus, by forming the DLC film 101 on the surface of the protrusion 22a, the friction resistance of the rotation transmitting portion 23 is improved, and stable rotation can be transmitted.

9 (A) and 9 (B) show the DLC film formation location when the mutual contact location is the rotation transmitting portion 23 of FIGS. 5 (A) to 5 (C). The rotation transmitting portion 23 is obtained by engaging a groove 13b (FIGS. 5A to 5C) provided on the spindle 3 and a protrusion 22b provided on the rotating shaft 22, and the groove 13b and the protrusion 22b. However, in this example, the DLC film 102 is formed on the surface of the protrusion 22b. The reason is that the surface of the protrusion 22b is exposed to the outside in the state before assembly, and therefore the process of forming the DLC film 102 is easy to perform. Thus, by forming the DLC film 102 on the surface of the protrusion 22b, the friction resistance of the rotation transmitting portion 23 is improved, and stable rotation can be transmitted.

FIG. 10 shows a DLC film formation location when the mutual contact location is a contact portion between the inner peripheral surface of the guide hole 30a (FIGS. 3A and 3B) and the outer peripheral surface of the posture operation member 31. FIG. The DLC film 103 is formed on the surface of the columnar pin 31 b in the posture operation member 31. The posture operation member 31 advances and retreats while being guided by the inner peripheral surface of the guide hole 30a. At that time, friction occurs due to contact with the inner peripheral surface of the guide hole 30a. When the DLC film 103 is formed on the surface of the columnar pin 31b, the friction coefficient between the inner peripheral surface of the guide hole 30a and the outer peripheral surface of the posture operation member 31 is reduced, and the posture operation member 31 is smoothly advanced and retracted. Since the surface of the columnar pin 31b is exposed to the outside in a state before assembly, the process of forming the DLC film 103 can be easily performed.

The DLC film 103 is also a DLC film when the mutual contact portion is a contact portion between the tip member 2 (FIG. 3A) and the posture operation member 31. As will be described later, during the posture changing operation of the distal end member 2, the distal end of the posture operating member 31 pushes the proximal end surface of the distal end member 2, whereby the distal end member 2 swings and changes its posture. At that time, a slip occurs between the proximal end surface of the distal end member 2 and the distal end surface of the columnar pin 31 b of the posture operation member 31. When the DLC film 103 is formed on the surface of the columnar pin 31b, the coefficient of friction between the proximal end surface of the distal end member 2 and the distal end surface of the columnar pin 31b is reduced, and the above-described sliding is performed satisfactorily. Changes are made smoothly.

FIG. 11 and FIG. 12 each show a DLC film forming portion of the rolling bearing 26 which is a rotation support member. FIG. 11 shows an example in which the DLC film 104 is formed on the rolling surfaces of the inner ring 26a and the outer ring 26b of the rolling bearing 26, and FIG. 12 shows an example in which the DLC film 105 is formed on the surface of the ball 26c of the rolling bearing 26. . Since both the transfer surfaces of the inner and outer rings 26a and 26b and the surface of the ball 26c are exposed to the outside before the assembly, the process of forming the DLC films 104 and 105 is easy to perform. As described above, when the DLC films 104 and 105 are formed on the transfer surfaces of the inner and outer rings 26a and 26b or the surface of the ball 26c, the wear resistance of the rolling bearing 26 is improved, and the rotating shaft 22 is stably and fast. It is possible to rotate. A DLC film may be formed on the rolling bearings 12 and 29 in the same manner.

The operation of this medical actuator will be described with reference to FIGS. 3 (A) and 3 (B). When the tool rotation drive source 41 (FIG. 6A) is driven, the rotation is transmitted to the spindle 13 via the rotation shaft 22, and the tool 1 rotates together with the spindle 13. The load acting on the tip member 2 when cutting the bone or the like by rotating the tool 1 is determined from the detected value of the wattmeter 47 (FIG. 6A), and the load detecting means 48 (FIG. 6A). Detected by. By controlling the feed amount of the entire medical actuator and the posture change of the distal end member 2 described later in accordance with the load value thus detected, the bone is cut while maintaining the load acting on the distal end member 2 appropriately. Can be processed.

In use, the posture changing drive source 42 (FIG. 6A) is driven to change the posture of the tip member 2 by remote control. For example, when the posture operating member 31 is advanced to the distal end side by the posture changing drive source 42, the housing 11 of the distal end member 2 is pushed by the posture operating member 31, and the distal end member 2 is directed downward in FIG. The posture is changed along the guide surfaces F1 and F2 toward the side. On the other hand, when the posture operation member 31 is retracted by the posture changing drive source 42, the housing 11 of the tip member 2 is pushed back by the elastic repulsive force of the restoring elastic member 32, and the tip member 2 is shown in FIG. The posture is changed along the guide surfaces F1 and F2 to the side facing upward. At this time, the pressure of the posture operation member 31, the elastic repulsive force of the restoring elastic member 32, and the reaction force from the retaining member 21 are acting on the tip member connecting portion 15, and the balance of these acting forces The posture of the tip member 2 is determined. The posture of the tip member 2 is detected from the detection value of the movement amount detector 45 by the posture detection means 46 (FIG. 6A). Therefore, the posture of the tip member 2 can be appropriately controlled by remote operation.

The posture operation member 31 is positioned eccentrically from the center line CL2 of the rotation shaft 22 and advances and retreats in a direction parallel to the center line CL2 of the rotation shaft 22 with its distal end in contact with the base end surface 11b of the housing 11 of the distal end member 2. To do. Then, when the distal end of the posture operation member 31 presses the proximal end surface 11b of the housing 11 which is a contact surface of the distal end member 2, the distal end member 2 swings around the center of curvature O and the posture is changed. At this time, the base end surface 11b of the housing 11 is perpendicular to the advancing / retreating direction of the posture operation member 31, that is, a perpendicular PL perpendicular to the tangent at the contact point P between the distal end member 2 and the posture operation member 31 and the center line CL2 of the rotary shaft 22. When the angle α is 0 °, no slip occurs between the tip member 2 and the posture operation member 31, and the tip member 2 cannot swing. However, if α> 0 °, the friction between the tip member 2 and the posture operation member 31 and the friction acting on the tip member connecting portion 15 are overcome, and the tip member 2 slips with respect to the posture operation member 31. It is possible to swing while moving. As described above, the DLC film 103 (FIG. 10) is formed on the surface of the columnar pin 31b of the posture operation member 31, and the friction between the tip member 2 and the posture operation member 31 is small. You can slide smoothly. Thereby, the attitude | position change of the front-end | tip member 2 is performed smoothly.

More specifically, there is an angle range in which the tip member 2 cannot slide with respect to the posture operation member 31, that is, a friction angle among the angles α due to resistance due to friction between the tip member 2 and the posture operation member 31. . This friction angle is proportional to the friction coefficient of the contact portion between the tip member 2 and the posture operation member 31. Therefore, the friction angle is reduced by forming the DLC film 103 (FIG. 10) on the surface of the columnar pin 31b of the posture operation member 31 and reducing the friction coefficient of the contact portion between the tip member 2 and the posture operation member 31. can do. If the friction angle is small, the posture change amount of the tip member 2 with respect to the amount of advancement / retraction of the posture operation member 31 is small, so that the posture of the tip member 2 can be controlled with fine resolution.

Since the posture operation member 31 is inserted through the guide hole 30a, the posture operation member 31 does not shift in the direction intersecting the longitudinal direction, and can always act properly on the tip member 2, and the tip member 2 posture change operation is performed accurately. Further, since the posture operation wire 31a constituting the posture operation member 31 is flexible, the posture changing operation of the tip member 2 is reliably performed even when the spindle guide portion 3 has a curved portion. Furthermore, since the center of the connecting portion between the spindle 13 and the rotating shaft 22 is at the same position as the center of curvature O of the guide surfaces F1 and F2, a force for pushing and pulling against the rotating shaft 22 by changing the posture of the tip member 2 is increased. Accordingly, the posture of the tip member 2 can be changed smoothly.

For example, when this medical actuator is used for cutting the medullary cavity of a bone in an artificial joint replacement operation, all or a part of the distal end member 2 is inserted into the patient's body. If the posture of the tip member 2 can be changed by remote control, the bone can be processed while the tool 1 is always held in an appropriate posture, and the artificial joint insertion hole can be finished with high accuracy. By using biocompatible materials for each component and forming DLC films 100 to 105 (FIGS. 7 to 12) having biocompatibility at mutual contact points, the posture of the tip member 2 can be changed smoothly. Therefore, it is suitable for use in surgery and the like.

The elongated spindle guide portion 3 needs to be provided with the rotating shaft 22 and the posture operation member 31 in a protected state. The rotating shaft 22 is provided at the center of the outer pipe 25, and the outer pipe 25, the rotating shaft 22, Since the guide pipe 30 accommodating the posture operation member 31 and the reinforcing shaft 34 are arranged side by side in the circumferential direction, the rotary shaft 22 and the posture operation member 31 are protected and the inside is made hollow. It is possible to secure rigidity while reducing the weight. Also, the overall balance is good.

Since the outer diameter surface of the rolling bearing 26 that supports the rotating shaft 22 is supported by the guide pipe 30 and the reinforcing shaft 34, the outer diameter surface of the rolling bearing 26 can be supported without using extra members. Moreover, since the preload is applied to the rolling bearing 26 by the spring elements 27A and 27B, the rotating shaft 22 made of a wire can be rotated at a high speed. Therefore, machining can be performed by rotating the spindle 13 at a high speed, the machining finish is good, and the cutting resistance acting on the tool 1 can be reduced. Since the spring elements 27A and 27B are provided between the adjacent rolling bearings 26, the spring elements 27A and 27B can be provided without increasing the diameter of the spindle guide portion 3.

In these first and second embodiments, the tool rotation drive source 41 and the posture change drive source 42 are provided in a common drive unit housing 4a. Therefore, the configuration of the entire medical actuator can be simplified. Only one of the tool rotation drive source 41 and the posture change drive source 42 may be provided in the drive unit housing 4a. Further, as will be described later, the tool rotation drive source 41 and the attitude change drive source 42 may be provided outside the drive unit housing 4a.

In the medical actuator of the present invention, since the posture operation member 31 has flexibility, even when the spindle guide portion 3 has a curved portion as shown in FIG. Only a part of the spindle guide 3 may be curved. If the spindle guide portion 3 is curved, it may be possible to insert the distal end member 2 to the back of the bone, which is difficult to reach in the straight shape, so that the hole for artificial joint insertion can be accurately processed in artificial joint replacement surgery. It becomes possible to finish. When the spindle guide portion 3 has a curved shape, the outer pipe 25, the guide pipe 30, and the reinforcing shaft 34 need to have a curved shape. The rotating shaft 22 is preferably made of a material that is easily deformed, and for example, a shape memory alloy is suitable.

13 (A) and 13 (B) show different configurations of the posture changing drive mechanism 4c. The tool rotation drive mechanism 4b shown in FIG. 13A has the same configuration as that shown in FIG. The posture changing drive mechanism 4 c is provided with a speed reduction mechanism 53 integrally with the posture changing drive source 42. The speed reduction mechanism 53 decelerates and outputs the rotation of the posture changing drive source 42, and the operation conversion mechanism 54A is directly connected to the output shaft 53a. The motion conversion mechanism 54A is a mechanism that converts the output of the speed reduction mechanism 53 from a rotational motion to a forward / backward motion. The motion conversion mechanism 54A in this example is a linear motion mechanism that converts the output of the speed reduction mechanism 53 from a rotary motion to a linear reciprocating motion and outputs the linear motion.

Specifically, the motion conversion mechanism 54A, which is a linear motion mechanism, includes a ball screw 57 having both ends supported by bearings 55 and one end coupled to the output shaft 53a of the speed reduction mechanism 53 via a coupling 56, and the ball A linear motion member is provided that includes a ball screw mechanism 59 including a nut 58 that engages with the screw 57, and is guided by the nut 58 so as to be movable in the axial direction of the ball screw 57 by a linear guide 60 (FIG. 13B). 61 is fixed. The linear motion member 61 is an output member of the motion conversion mechanism 54 </ b> A, and the proximal end of the posture operation member 31 is in contact with the contact portion 61 a formed of the distal end surface of the linear motion member 61.

The rotation of the output shaft 53a of the speed reduction mechanism 53 is converted into a linear motion by the ball screw mechanism 59, and the linear motion member 61 moves linearly along the linear guide 60 (FIG. 13B). When the linear motion member 61 moves to the left side of FIG. 13A, the posture operation member 31 pushed by the linear motion member 61 moves forward, and when the linear motion member 61 moves to the right side, the restoring elasticity The posture operation member 31 is retracted by being pushed back by the elastic repulsive force of the member 32.

As shown in FIG. 13B, a linear scale 62 is installed on the linear motion member 61, and the scale of the linear scale 62 is read by a linear encoder 63 fixed to the drive unit housing 4a. The linear scale 62 and the linear encoder 63 constitute position detecting means 64 that detects the advancing / retreating position of the posture operation member 31. Precisely, the output of the linear encoder 63 is transmitted to the advance / retreat position estimation means 65, and the advance / retreat position estimation means 65 estimates the advance / retreat position of the posture operation member 31. That is, the position detection unit 64 detects the operating position of the linear motion member 61 that is a power transmission unit between the speed reduction mechanism 53 and the posture operation member 31, and estimates the advance / retreat position of the posture operation member 31 from the detection result.

The advance / retreat position estimation means 65 has relationship setting means (not shown) in which the relationship between the advance / retreat position of the posture operation member 31 and the output signal of the linear encoder 63 is set by an arithmetic expression or a table, etc. The advance / retreat position of the posture operation member 31 is estimated from the signal using the relationship setting means. The advance / retreat position estimation means 65 may be provided in the controller 5 (FIGS. 1 and 2) or may be provided in an external control device. The controller 5 controls the attitude changing drive source 42 based on the detection value of the advance / retreat position estimating means 65.

According to the configuration of the posture changing drive mechanism 4c, the posture operating member 31 is moved back and forth as follows. That is, the rotation of the posture changing drive source 42 is decelerated by the speed reduction mechanism 53, further converted from a rotational motion to a linear advance / retreat motion by the motion conversion mechanism 54A, and transmitted to the linear motion member 61 as an output member. The forward / backward movement of the linear motion member 61 is transmitted from the contact portion 61a to the proximal end of the posture operation member 31, and the posture operation member 31 moves forward / backward. Since the speed reduction mechanism 53 is provided, a large acting force can be applied to the linear motion member 61 by generating a large torque even if the torque output from the attitude changing drive source 42 is small. Therefore, the posture operation member 31 can be reliably advanced and retracted, and the tool 1 provided on the tip member 2 shown in FIG. Further, the posture changing drive source 42 can be miniaturized, and the entire medical actuator can be made compact.

In particular, a rotary actuator is used as the posture changing drive source 42, and the speed reduction mechanism 53 is combined with a motion conversion mechanism 54A that converts the output thereof into a forward / backward movement. The posture conversion operation is performed by the motion conversion mechanism 54A via the linear motion member 61. Since the member 31 is moved back and forth, the entire medical actuator can be made even more compact.

The attitude of the tip member 2 (FIG. 3A) is obtained from the advance / retreat position of the attitude operation member 31 detected by the position detection means 64. Positioning accuracy of the tool 1 can be improved by performing feedback control in which the detected value of the position detecting means 64, more precisely, the detected value of the linear encoder 63 is fed back to the controller 5 to control the output amount of the attitude changing drive source 42. Can be made.

14 (A) and 14 (B) show different examples of the motion conversion mechanism. The motion conversion mechanism 54B has both a function of converting a rotational motion into a forward / backward motion and a deceleration function. Therefore, the speed reduction mechanism 53 is not attached to the posture changing drive source 42. The motion conversion mechanism 54B includes a worm 67 having both ends supported by bearings 55 and one end connected to the output shaft 42a of the attitude changing drive source 42 via a coupling 56, and the worm 67 supported by the support shaft 68a. And a meshing worm wheel 68. The worm wheel 68 is an output member of the motion conversion mechanism 54 </ b> B, and the base end of the posture operation member 31 is in contact with a contact portion 68 b formed from the distal end surface of the worm wheel 68. The worm wheel 68 has a shape in which teeth are provided only at a part of the circumference, and has an opening 68c through which the rotary shaft 22 is inserted.

Rotation of the output shaft 42a of the attitude changing drive source 42 is decelerated by a reduction mechanism including a worm 67 and a worm wheel 68, and is transmitted to the worm wheel 68 as an output member. While the worm wheel 68 swings while the contact portion 68b of the worm wheel 68 is in sliding contact with the posture operation member 31, the posture operation member 31 is moved forward and backward. That is, when the contact portion 68b rotates to the left in FIG. 14A, the posture operation member 31 pushed by the contact portion 68b moves forward, and when the contact portion 68b rotates to the right side, The posture operation member 31 is retracted by being pushed back by the elastic repulsive force of the elastic member 32 (FIG. 3A).

The advance / retreat position of the posture operation member 31 is detected by the position detection means 64. In the case of this example, the position detecting means 64 includes a detected portion 69 provided on the back surface of the worm wheel 68, and a detecting portion 70 that is fixed to the drive portion housing 4a and detects the displacement of the detected portion 69. It becomes. The position detecting means 64 may be optical or magnetic. Precisely, the output of the detection unit 70 is transmitted to the advance / retreat position estimation means 65, and the advance / retreat position estimation means 65 estimates the advance / retreat position of the posture operation member 31. That is, the position detection means 64 detects the operating position of the worm wheel 68 that is a power transmission means between the speed reduction mechanism and the posture operation member 31, and estimates the advance / retreat position of the posture operation member 31 from this detection result.

This motion conversion mechanism 54B also serves as a speed reduction mechanism. In other words, it can be said that the mechanism in which the worm 67 and the worm wheel 68 are combined is a speed reduction mechanism to which an operation conversion function is added. Thus, by integrating the speed reduction mechanism and the motion conversion mechanism, the functional portions for speed reduction and motion conversion can be made compact and compact. By using the worm wheel 68 as an output member, the number of parts can be reduced. Further, the speed reduction mechanism including the worm 67 and the worm wheel 68 can take a large reduction ratio.

FIG. 15 and FIGS. 16A and 16B show a third embodiment in which the configurations of the tool rotation drive mechanism and the posture change drive mechanism are different. In the first and second embodiments, the tool rotation drive source 41 of the tool rotation drive mechanism 4b and the attitude change drive source 42 of the attitude change drive mechanism 4c are provided in the drive unit housing 4a. On the other hand, in the third embodiment shown in FIGS. 15, 16A and 16B, the tool rotation drive source 41 and the posture change drive source 42 are provided in a drive source housing 80 different from the drive unit housing 4a. It has been.

As shown in FIG. 16A, the tool rotation drive mechanism 81 according to the third embodiment can rotate the output shaft 41a of the tool rotation drive source 41 provided in the drive source housing 80 by using a flexible tool rotation. It transmits to the base end of the rotating shaft 22 in the drive part housing 4a by the inner wire 84 (FIG. 17) of the property wire 82. The tool rotating flexible wire 82 has a structure shown in FIG. 17, for example. That is, the flexible inner wire 84 is rotatably supported by the plurality of rolling bearings 86 at the center of the flexible outer tube 83. Both ends of the inner wire 84 are connected to the output shaft 41 a of the tool rotation drive source 41 and the base end of the rotation shaft 22, respectively. Between the rolling bearings 86, spring elements 87A and 87B for generating a preload in the rolling bearings 86 are provided. The spring elements 87A and 87B are, for example, compression coil springs. There are an inner ring spring element 87A for generating a preload on the inner ring of the rolling bearing 86 and an outer ring spring element 87B for generating a preload on the outer ring, which are arranged alternately. Thus, the inner wire 84 can be rotated at a high speed by applying a preload to the rolling bearing 86 by the spring elements 87A and 87B. A commercially available flexible shaft may be used.

In addition, as shown in FIG. 16A, the posture changing drive mechanism 91 according to the third embodiment is configured to rotate the posture changing drive source 42 provided in the drive source housing 80 by changing the posture changing flexible wire. 92 is transmitted to the speed reduction mechanism 53 installed in the drive unit housing 4a by the inner wire 94 (FIG. 18), and further transmitted from the speed reduction mechanism 53 to the operation conversion mechanism 54 of the drive unit housing 4a. The motion conversion mechanism 54 of this example is the same configuration as the motion conversion mechanism 54A of FIGS. 13A and 13B, and is a linear motion mechanism that converts the rotation of the inner wire 94 into a linear reciprocating motion and outputs it. ing. Parts having the same configurations as those in FIGS. 13A and 13B are shown with the same reference numerals attached to a part thereof. As the operation conversion mechanism 54, another operation conversion mechanism such as the operation conversion mechanism 54B may be adopted.

The posture changing flexible wire 92 has the same structure as the tool rotating flexible wire 82, for example, the structure shown in FIG. That is, the flexible inner wire 94 is rotatably supported by the plurality of rolling bearings 96 at the center of the flexible outer tube 93. Then, both ends of the inner wire 94 are connected to the output shaft 42a of the attitude changing drive source 42 and the input shaft 53b of the speed reduction mechanism 53, respectively, as shown in FIG. Between the rolling bearings 96, spring elements 97A and 97B for generating a preload on the rolling bearings 96 are provided. The spring elements 97A and 97B are, for example, compression coil springs. There are an inner ring spring element 97A for generating a preload on the inner ring of the rolling bearing 96 and an outer ring spring element 97B for generating a preload on the outer ring, which are arranged alternately. Thus, the inner wire 94 can be rotated at a high speed by pre-loading the rolling bearing 96 with the spring elements 97A and 97B. A commercially available flexible shaft may be used.

The inner wire 94 of the posture changing flexible wire 92 is twisted during rotation transmission, and a rotation phase difference is generated between the rotation transmission upstream side and the downstream side. However, as shown in FIG. 16A, since the speed reduction mechanism 53 is provided on the downstream side of the flexible wire 92, the rotational phase difference becomes smaller on the output side of the speed reduction mechanism 53. Therefore, the influence of the twist of the flexible wire 92 does not appear greatly in the linear motion member 61 that is the output member, and the posture operation member 31 can be advanced and retracted with high accuracy.

Thus, by providing the tool rotation drive source 41 and the posture changing drive source 42 outside the drive unit housing 4a, the drive unit housing 4a can be reduced in size. Therefore, the handleability at the time of operating a medical actuator with the drive part housing 4a can be improved. The controller 5 that controls the tool rotation drive source 41 and the posture change drive source 42 is connected to a drive source housing 80 as shown in FIG.

19A and 19B show a fourth embodiment in which the configuration for changing the posture of the tip member 2 is different. As shown in FIG. 19B, this medical actuator is provided with two guide pipes 30 at circumferential positions in the outer pipe 25 that are 180 degrees in phase with each other, and is an inner diameter hole of the guide pipe 30. In the guide hole 30a, a posture operation member 31 composed of the same posture operation wire 31a and columnar pin 31b is inserted so as to be able to advance and retreat. Between the two guide pipes 30, a plurality of reinforcing shafts 34 are arranged on the same pitch circle C as the guide pipe 30. The restoring elastic member 32 is not provided. The guide surfaces F1 and F2 are spherical surfaces whose center of curvature is the point O, or cylindrical surfaces whose axis is the X axis passing through the point O.

The drive unit 4 (not shown) is provided with two posture change drive sources 42 (not shown) for individually moving the two posture operation members 31 forward and backward, and these two posture change drives. The posture of the tip member 2 is changed by driving the sources 42 in opposite directions. For example, when the upper posture operation member 31 in FIG. 19A is advanced to the distal end side and the lower posture operation member 31 is retracted, the upper posture operation member 31 pushes the housing 11 of the distal end member 2. Thus, the posture of the tip member 2 is changed along the guide surfaces F1 and F2 to the side with the tip side facing downward in FIG.

Conversely, when both posture operation members 31 are moved back and forth, the housing 11 of the tip member 2 is pushed by the lower posture operation member 31, and the tip member 2 is directed upward in FIG. 19A. The posture is changed along the guide surfaces F1 and F2 to the side. At that time, the pressure of the two upper and lower posture operating members 31 and the reaction force from the retaining member 21 are acting on the tip member connecting portion 15, and the posture of the tip member 2 is determined by the balance of these acting forces. Is done. In this configuration, the housing 11 of the tip member 2 is pressurized by the two posture operation members 31, so that the posture stability of the tip member 2 is improved as compared with the embodiment in which the pressure is applied by only one posture operation member 31. Can be increased.

FIGS. 20A and 20B show a fifth embodiment in which the configuration for changing the posture of the tip member 2 is further different. As shown in FIG. 20B, this medical actuator is provided with three guide pipes 30 at circumferential positions in the outer pipe 25 that are in a phase of 120 degrees with each other, and is an inner diameter hole of the guide pipe 30. A posture operation member 31 similar to the above is inserted into the guide hole 30a so as to freely advance and retract. Between the three guide pipes 30, a plurality of reinforcing shafts 34 are arranged on the same pitch circle C as the guide pipes 30. The restoring elastic member 32 is not provided. Guide surfaces F1 and F2 shown in FIG. 20A are spherical surfaces whose center of curvature is a point O, and the tip member 2 can tilt in any direction.

The drive unit 4 includes three posture change drive sources 42 (42U, 42L, 42R) for individually moving the three posture operation members 31 (31U, 31L, 31R) shown in FIG. 22 (A), (B) and FIGS. 23 (A), (B)) are provided, and the posture change of the tip member 2 can be performed by driving these three posture change drive sources 42 in conjunction with each other. Do.

For example, when one posture operation member 31U on the upper side in FIG. 20B is advanced to the distal end side and the other two posture operation members 31L and 31R are moved backward, as shown in FIG. When the housing 11 of the tip member 2 is pushed by the posture operation member 31U, the tip member 2 changes its posture along the guide surfaces F1 and F2 to the side where the tip side faces downward in FIG. At this time, each posture changing drive source 42 (FIG. 22B) is controlled so that the amount of advancement / retraction of each posture operation member 31 is appropriate. When each posture operation member 31 is moved back and forth, the housing 11 of the tip member 2 is pushed by the left and right posture operation members 31L and 31R, so that the tip member 2 moves to the side where the tip side is upward in FIG. The posture is changed along the guide surfaces F1 and F2.

Further, when the left posture operation member 31L is advanced to the distal end side and the right posture operation member 31R is moved backward while the upper posture operation member 31U is stationary, the distal end member 2 is moved by the left posture operation member 31L. When the housing 11 is pressed, the tip member 2 changes its posture along the guide surfaces F1 and F2 to the right, that is, the side facing the back side of the paper surface in FIG. When the left and right posture operation members 31L and 31R are moved back and forth, the housing 11 of the tip member 2 is pushed by the right posture operation member 31R, so that the tip member 2 moves along the guide surfaces F1 and F2 toward the left side. Change the posture.

Thus, by providing the posture operation member 31 at three positions in the circumferential direction, the posture of the tip member 2 can be changed in the directions of the upper, lower, left and right axes (X axis, Y axis). At that time, the pressure of the three posture operating members 31 and the reaction force from the retaining member 21 are acting on the tip member connecting portion 15, and the posture of the tip member 2 is determined by the balance of these acting forces. The In this configuration, since the pressure is applied to the housing 11 of the tip member 2 by the three posture operation members 31, the posture stability of the tip member 2 can be further improved. If the number of posture operation members 31 is further increased, the posture stability of the tip member 2 can be further enhanced.

21 (A) and 21 (B) show a sixth embodiment in which the internal structure of the spindle guide portion 3 is different from that in FIGS. 20 (A) and 20 (B). In the spindle guide portion 3 of this medical actuator, the hollow hole 24 of the outer pipe 25 shown in FIG. 21 (A) has a circular hole portion 24a at the center portion and the circular hole portion as shown in FIG. 21 (B). It consists of three groove-like portions 24b that are recessed from the circumferential position forming a phase of 120 degrees to the outer diameter side on the outer periphery of 24a. The peripheral wall at the tip of the groove-like portion 24b has a semicircular cross section. And the rotating shaft 22 and the rolling bearing 26 are accommodated in the circular hole 24a, and the attitude | position operation member 31 (31U, 31L, 31R) is accommodated in each groove-shaped part 24b.

Since the outer pipe 25 has the above-described cross-sectional shape, the thickness t of the outer pipe 25 other than the groove-like portion 24b is increased, and the secondary moment of the outer pipe 25 is increased. That is, the rigidity of the spindle guide portion 3 is increased. Thereby, the positioning accuracy of the tip member 2 can be improved and the machinability can be improved. Further, since the guide pipe 30 is disposed in the groove-like portion 24b, the guide pipe 30 can be easily positioned in the circumferential direction, and the assemblability is good.

When the posture operation members 31 are provided at three places in the circumferential direction as in the fifth embodiment shown in FIGS. 20A and 20B and the sixth embodiment shown in FIGS. The posture changing drive mechanism 4c can be configured as shown in FIGS. 22A and 22B or FIGS. 23A and 23B, for example. That is, the posture changing drive mechanism 4c shown in FIG. 22 (A) has three types shown in FIG. 22 (B) for individually moving the posture operating members 31 (31U, 31L, 31R) shown in FIG. The posture changing drive sources 42 (42U, 42L, 42R) are arranged in parallel on the left and right, and the levers 43b (43bU, 43bL, 43bR) corresponding to the posture changing drive sources 42 are rotated around a common support shaft 43a. The force of the output rod 42a of each posture changing drive source 42 acts on an action point P1 (P1U, P1L, P1R) that is provided freely and has a long distance from the support shaft 43a in each lever 43b, and the distance from the support shaft 43a. Is configured to apply a force to the posture operating member 31 at a short force point P2 (P2U, P2L, P2R). Thereby, the output of each posture change drive source 42 can be increased and transmitted to the corresponding posture operation member 31. The rotary shaft 22 passes through an opening 44 formed in the lever 43bU for the upper posture operation member 31U.

The posture changing drive mechanism 4c shown in FIG. 23A has three posture changing drive sources 42 (42U, 42L, 42R) for individually moving the posture operating members 31 (31U, 31L, 31R) forward and backward. As shown in FIG. 23B, three motion conversion mechanisms 54 (54U, 54L, 54R) corresponding to the posture changing drive sources 42 are provided. FIGS. 23A and 23B are examples in which the motion conversion mechanism is a linear motion mechanism type motion conversion mechanism 54A shown in FIGS. 13A and 13B. The motion conversion mechanisms 54 (54U, 54L, 54R) are arranged radially about the rotation shaft 22.

As described above, the preferred embodiments have been described with reference to the drawings. However, those skilled in the art will readily assume various changes and modifications within the obvious scope by looking at the present specification. Accordingly, such changes and modifications are to be construed as within the scope of the invention as defined by the appended claims.

DESCRIPTION OF SYMBOLS 1 ... Tool 2 ... Tip member 3 ... Spindle guide part 4a ... Drive part housing 5 ... Controller 11a ... Guided part 13 ... Spindle 13a ... Projection 13b ... Groove 15 ... Tip member connection part 21a ... Guide part 22 ... Rotating shaft 22a, 22b ... projection 23 ... rotation transmission part 26 ... rolling bearing (rotation support member)
26a ... Inner ring 26b ... Outer ring 26c ... Ball 30 ... Guide pipe 30a ... Guide hole 31 ... Posture operation member 31a ... Posture operation wire 41 ... Tool rotation drive source 42 ... Posture change drive source 100-105 ... DLC film CL1 ... Spindle Center line CL2 ... center line F1, F2 of rotation axis ... guide surface O ... center of curvature P ... contact point PL ... perpendicular line

Claims (14)

An elongated spindle guide part, a tip member that is attached to the tip of the spindle guide part via a tip member connecting part so as to change the posture and rotatably supports the tool, and a tool rotation drive source that rotates the tool And a posture changing drive source for operating the posture of the tip member,
The tip member rotatably supports a spindle that holds the tool, and the spindle guide portion includes a rotation shaft that transmits the rotation of the tool rotation drive source to the spindle, and guide holes that penetrate both ends. A flexible posture operation member, which has an inner end and moves forward and backward by contacting and moving the tip member in contact with the tip member, is inserted into the guide hole so as to freely move forward and backward. A medical actuator that moves forward and backward with a posture-changing drive source,
A medical actuator in which a DLC film is formed on the surface of at least one of a plurality of parts that move relative to each other. 2. The tip member connecting portion according to claim 1, wherein the tip member connecting portion includes a guide portion on the spindle guide portion side and a guided portion on the tip member side of the spindle. A spherical or cylindrical guide surface having a center of curvature located on the center line is in contact with each other, and a DLC film is provided on the guide surface which is the outer peripheral surface of the guide surface of the guide portion and the guide surface of the guided portion. The formed medical actuator. 2. The rotation transmitting portion that connects the spindle and the rotating shaft so as to be able to transmit rotation is provided as one of the mutual contact portions according to claim 1, and the rotation transmitting portion is provided on one of the spindle and the rotating shaft. A medical actuator having a structure in which a protrusion and a groove provided on the other are engaged with each other to transmit rotation, and a DLC film is formed on the surface of the protrusion. 2. The rotation transmitting portion that connects the spindle and the rotation shaft so as to be able to transmit rotation, wherein one of the mutual contact portions is a protrusion provided on each of the spindle and the rotation shaft. A medical actuator having a structure in which rotation is transmitted by engaging each other, and a DLC film is formed on the surface of both or one of the protrusion of the spindle and the protrusion of the rotation shaft. 2. The medical actuator according to claim 1, wherein one of the mutual contact locations is a contact portion between an inner peripheral surface of the guide hole and an outer peripheral surface of the posture operation member, and a DLC film is formed on the outer peripheral surface of the posture operation member. . In Claim 1, when an angle formed by a perpendicular perpendicular to a tangent at a contact point between the tip member and the posture operation member and a center line of the rotating shaft is α, α> 0 ° and the mutual One of the contact locations is a contact portion between the tip member and the posture operation member, and a medical actuator in which a DLC film is formed on both or one surface of the contact portion on the tip member side and the contact portion on the posture operation member side. 2. The medical actuator according to claim 1, wherein one of the mutual contact portions is a rotation support member that rotatably supports the rotation shaft in the spindle guide portion. 8. The medical actuator according to claim 7, wherein the rotation support member is a rolling bearing, and a DLC film is formed on both or one of the surface of the ball of the rolling bearing and the rolling surface of the inner and outer rings. The medical actuator according to claim 1, wherein each component is made of a biocompatible material. 2. The medical actuator according to claim 1, wherein the spindle guide portion has a curved portion. 2. The medical actuator according to claim 1, wherein the DLC film is formed by physical vapor deposition. 12. The medical actuator according to claim 11, wherein the physical vapor deposition method is an unbalanced magnetron sputtering method. The medical actuator according to claim 10, wherein an intermediate layer containing chromium and tungsten is formed between a base material and the DLC film. 2. The medical actuator according to claim 1, wherein the DLC film has a thickness of 0.3 to 3 μm.

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